A liquid crystal display device has developed quickly and has become a mainstream panel display device. Up to now, the liquid crystal display device has developed into several types such as Twisted Nematic (TN) type, Advanced Dimension Switch (ADS) type, High-Advanced Dimension Switch (HADS) type and In-Plane Switch (IPS) type. The driving modes and display effects thereof are not the same, and each type has its strong points. The ADS type and the HADS type liquid crystal display devices present excellent display capability and effect with their unique structure characteristics and driving principles.
The main difference between the ADS type and the HADS type liquid crystal display device lies in that, a slit common electrode in the HADS type liquid crystal display device is located above a plate pixel electrode, while in the ADS type liquid crystal display device, a slit pixel electrode is located above a plate common electrode. Compared to the HADS type liquid crystal display device, in the existing ADS type liquid crystal display device, because the common electrode does not cover a data line and a gate line, loads of the data line and the gate line are relatively small, which is more suitable for design of large dimension.
The structure of the existing ADS type liquid crystal display device for example is as shown in FIG. 1a to FIG. 1c. It comprises an upper substrate 1 and a lower substrate 2 arranged opposite to each other, a gate line 21, a data line 22, a common electrode 23 and a pixel electrode 24 located on the upper substrate 2. A color filtering layer (not shown in the figures) and a black matrix 11 are arranged on the upper substrate 1. The black matrix 11 is directly opposite to the data line 22 and the gate line 21. However, the above ADS type liquid crystal display device has some shortcomings. For example, the upper substrate may be shifted by pressing the display panel vigorously. If the black matrix 11 located above the gate line 21 is relatively narrow, light leakage may occur easily. Hence, in order to prevent light leakage, the black matrix 11 is required to have a relatively large width generally, however, if so, aperture ratio and light transmissivity will be reduced.